Boat crane

ABSTRACT

Straddle-type boat crane for lowering and lifting boats into and out of the water and for transporting them to and from the water. The crane includes fixed position forward and rear hoists, the latter being free of any fixed or movable transverse member and providing unlimited inside clear height at all times for ease and convenience in handling boats having high superstructures or tall spars.

[ Feb. 8, 1972 United States Patent Klein .214/394 X .....2l4/394 .214/396 X [541 BOAT CRANE 3,044,567 7/1962 Reed et 3 I81 717 5/1965 Kumferman....... [72] Inventor: Carl Robert Klein 403 Northwest Street,

Benevue Ohio g 3,329,284 7/1967 Bogart,.lr. et Dec. 29, 1969 [21] Appl. No.: 888,776

Primary Examiner-Albert J. Makay [22] Filed:

Attorney-Bosworth, Sessions, Herrstrom and Cain ABSTRACT e boat crane for lowering and lifting boats into and out of the water and for transporting them to and from the water. The crane includes fixed position forward and rear hoists, the latter being free of any fixed or movable transverse roviding unlimited inside clear height at all times for ease and convenience in handling boats having high superstructures or tall spars.

e m b m m m 40 4 Hu 43W4 9 9 2W2!- 4 n 1. W 1M3 ,m m B m2 m 5 in c f u e f. "m" e "um R Km LITM mew Um 11] 1 2 00 6 www w UNITED STATES PATENTS Steam....................................214/394 5 Claims, 3 Drawing Figures BOAT CRANE BACKGROUND OF THE INVENTION In the use and enjoyment of small boats and watercraft, it is often necessary and/or desirable to remove and return the boat from and to the water. Numerous methods and ap paratus, including cranes, hoists, and marine railways, have been devised for accomplishing this general purpose. This invention relates to a crane of a general type presently known and used. The general type is characterized by means for lowering and raising two or more loop slings into and out of the water. The slings are lowered into the water, for example, and suspended there in a position permitting a boat to be floated into the loops formed by the slings. The slings are then raised, lifting the boat from the water. The boat is returned to the water by lowering the boat and slings into the water so that the boat is able to be floated out of the sling loops.

This invention relates particularly to a crane of the general type described which is a wheeled straddle-type vehicle adapted to be self-propelled or moved about by a separate tractor. Such a crane is adapted to lift a boat from a boat well or slip which has a runway extending along each side of the well and boat. The crane is provided with wheels which run on both runways so that the crane straddles the well and the boat to be lifted.

One of the problems connected with the use of such a straddie-type boat crane is adapting the crane to accept and to straddle boats having high superstructures and/or tall spars. All straddle-type boat cranes known to applicant require transverse structural members at the rearward end of the crane, i.e., the end through which the boat enters, which members tend to limit the height of boats which can be handled. Although such transverse members are placed as high as reasonably possible above the water, there is a practical limit to this height. Also, it is highly desirable that such cranes be able to enter and carry boats into storage and work buildings, thus limiting overall crane height to conventional building door heights.

The problem is particularly acute with sailboats having tall spars. Known cranes of the general type to which this invention relates either have fixed interfering transverse members which require the mast of a sailboat to be unstepped, or they embody transverse members at the aft or entry end which can be opened to admit the spar and riggings toward the forward end of the crane. Unrigging and unstepping a tall spar can be a difficult and expensive operation. Movable transverse members, in the nature of a gate, are complicated, often troublesome, and increase the inconvenience and cost of the crane and its operation and use. U.S. Pat. No. Re. 25,276 to R. A. Steam typifies the fixed aft transverse member design. The movable, but essential, transverse member design is shown in U.S. Pat. No. Re. 25,081, also to R. A. Steam.

Past efforts in solving this problem have, to applicants knowledge, been devoted exclusively to providing as convenient and as simple a transverse gate member as possible. Past designers and builders of such cranes, including R. A. Steam referred to above, acknowledge and teach the necessity of a rigid transverse member or members at the aft or entering end of the crane and forming an integral and essential part of the crane structure when it is lifting, supporting, and lowering a boat and/or traveling. The gate or movable feature, if any, of these transverse members is usable only when the crane is not traveling and, particularly, when the crane is supporting no load, thus limiting the utility as well as increasing the expense of operating such a crane.

BRIEF SUMMARY OF THE INVENTION This invention relates to straddle-type cranes adapted to straddle a boat well and a boat in it. Cranes embodying this invention comprise a frame having a pair of laterally opposite and spaced apart longitudinal side rails. The side rails may be rigidly connected together at one end by a transverse member to form a generally U-shaped frame. The whole frame is supported on wheels and/or wheels and folding legs. A hitch may be provided at one end of the frame if the crane is to be connected to a truck or tractor. The other end of the frame is entirely open and free of any transverse member. This is the aft end and the end through which boats to be handled generally enter and leave.

At a point generally forward of the midpoint of the length of the side rails and between the ends of the frame they comprise, a forward hoist is provided. The forward hoist comprises an upwardly extending mast or tower fixed to and mounted on each side rail at laterally opposite points on the frame. The upper ends of these towers are joined together by a transverse member. The two towers and transverse member joining their upper ends are rigidly connected together and with the frame so that they maintain the lateral spacing of the side rails and also restrain the side rails against rotational movement about their longitudinal axes.

At the aft end of the frame, an upwardly extending tower or mast member is fixedly mounted on each side rail. The two aft towers do not encrouch upon the inside clear height between the side rails and are free of any rigid interconnection between them, directly contrary to the teachings of the prior art.

A sling loop is suspended from the forward and from the aft hoists. Each sling comprises a flexible wide strap or web for engaging with the boat and is supported by means of adjustable length coming from opposite sides of its associated hoist. By letting out the cables, the sling is permitted to hang down into the water generally in the shape of a catenary loop spanning the space between the side rails.

Because the aft hoist is free of any members blocking the entrance of boats having high superstructures or stepped spars, the loading and unloading of the crane is simple, convenient, and able to be accomplished by a minimum of personnel. Removal of high superstructure and unstepping of spars is not required and it is not necessary to close or reconnect any movable transverse members of the crane in order to prepare it for traveling. In addition, the crane structure itself can be limited to reasonable heights, permitting its normal use into and out of conventional workshops and storage buildings.

Contrary to known straddle-type boat cranes and to the teachings of primary designers and inventors of such cranes, this invention permits the elimination of troublesome transverse members heretofore considered necessary to the successful operation and use of such cranes. The invention comprehends side rails consisting of tubular members having large average transverse dimensions and adapted to be held against displacement relative to each other and rotational movement about their axes so that the side members can, in turn, support the towers of the aft hoist in an upright position clear of the inside space between the aft end of the side rails. It has been found that the numerous problems formerly thought to be connected with elimination of rigid transverse structural members at the aft end of such cranes, be they permanent or openable, can be solved by the use of such tubular side rail members. While this may appear to be a simple expedient, it is completely contrary to former understanding of and concepts applied in this type of boat crane and, indeed, was considered to be an undesirable and unprofitable approach to the problems involved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a boat crane comprising a preferred embodiment of this invention;

FIG. 2 is a side elevation view of the crane shown in FIG. 1; and

FIG. 3 is an aft end elevation view of the crane of FIG. 1.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT A preferred embodiment of this invention consists of a twowheel trailer-type boat crane having a pair of wheels 10 at its aft end and a pair of folding legs 11 at its fonvard end,

together with a hitch pin 12 and mounting structure 13. The trailer consists of a generally U-shaped frame indicated generally at 14 and made up of a pair of laterally opposite and parallel side rails 15 and 16. A transverse forward member 17 extends between and connects the laterally opposite forward ends of side rails 15 and 16 to form the integral and substantially rigid U-shaped frame 14. The side rails 15 and 16 are formed of tubular elements having a large-diameter cross section. In one model of the preferred embodiment having a rated lifting capacity of 15 tons and an inside clear length of approximately 31 feet, the side rails comprise 14-inch diameter steel tubes. It is convenient to form the forward transverse member 17 joining the ends of the side rails 15 and 16 of similar tubular material. As shown in the drawings, transverse and side rail members l5, l6, and 17 are joined by circumferentially arranged bolts passing through suitable openings in abutting annular flanges 18 for convenience in assembling and disassembling the crane for shipment between the distant points and/or storage.

A forward hoist indicated generally at 20 is located on and mounted to side rails 15 and 16 at laterally opposite points between their ends. Forward hoist 20 comprises a pair of towers 21 and 22 extending upwardly from the side rails 15 and 16, respectively. Towers 21 and 22 preferably are made up of spaced-apart box beams 23 and 24 and suitably interconnected by generally transverse braces 25. Each tower 21 and 22 is removably fixed and fastened to its associated side rail by means of saddles 26 permanently mounted on the side rails. Each saddle has an upwardly facing flange 27 adapted for abutting engagement with a corresponding flange 28 on the lower end of a box beam. The upper ends of the two generally vertical towers 21 and 22 are connected together by a horizontal truss structure indicated generally at 30, preferably comprised of flanged or box beams 31 able to withstand substantial bending and compression loads. Comer braces 32 at the upper corners of the forward hoist are provided for increased rigidity.

Forward hoist 20 can be easily removed for shipment, for example, but, when installed, is not movable forward or aft on and along the side rails. When assembled with U-shaped frame 14, the forward hoist, including its two towers 21 and 22 and transverse member 30, comprises an integral and rigidly interconnected part of the crane. Forward hoist 20 aids in insuring the fixed relationship of the two side rails 15 and 16 to each other and in resisting any tendency of the side rails to rotate or twist about their axes. In addition, forward hoist 20 serves as the mounting and supporting structure for the cable drums, drives and drive motors for lifting and raising the slings as is described more fully below.

The aft hoist indicated generally at 33 consists of a pair of generally vertically standing towers 34 and 35, one at the aft end of each side rail. Each tower is free and independent of the other. There is no transverse structural member interconnecting aft hoist towers 34 and 35 or aft end of side rails 15 and 16. Aft towers 34 and 35 are rigidly fastened to the ends of the cylindrical side rails 15 and 16, respectively, so that the large-diameter tubular section of the side rails serves to hold the towers upright against any side loads imposed upon them. Aft towers 34 and 35 lie substantially in a plane normal to the axes of side rails 15 and 16. The towers themselves, together with strengthening and reinforcing plates 39, strengthen the tubes against any tendency of their tubular sections to collapse due to forces imposed on the aft hoist during operation of the crane.

The aft end of the crane as described has unlimited inside clear height at aft hoist 33. In the model of the preferred embodiment referred to above, the inside clear height of forward hoist 20 is approximately 16 feet. The inside clear width between side rails 15 and 16 may be as much as 18 feet in the particular model referred to.

The forward and aft hoists support and provide means for raising and lowering a pair of loop slings adapted to pass beneath the boat and up either side of the boat when it is to be held by the crane. The forward sling, indicated generally at 36, spans the space between the side rails and beneath the forward hoist. The rear sling, indicated generally at 37, does the same thing at the rear hoist.

Each sling preferably comprises a wide rubber-faced, cablereinforced web or strap 38 adapted to lie smoothly against the outer surface of a boat hull without damaging or marking it and/or concentrating loads that might tend to harm the boat when its entire weight is supported in the slings.

The ends of straps 38 of the forward and aft slings 36 and 37 nearest side rail 15 are fastened by means of bails 42 to a load or sling beam 43. The other ends of both straps 38 are fastened by means of bails 42 to a load or sling beam 44. Sling beams 43 and 44 preferably have a high resistance to bending. Bails 42 fit loosely around the beams and can slide fore and aft along them to permit positioning the slings at any desired spacing and fore-and-aft location. Obviously, more than two slings may be attached to the sling beams. The use of sling beams 43 and 44 provides adjustable sling spacings and positions while permitting fixed forward and aft hoist structures which contribute so much to the unitary nature of the crane structure.

The ends of sling beams 43 and 44 are each provided with a block and pulley 45. In the case of aft hoist 33, a cable 41 is dead-ended at the upper end of each tower, passes through block and pulley 45 at the aft end of the adjacent sling beam, returns to a pulley 46 supported in the upper end of its associated tower directing cable 41 downwardly to and around a pulley 47 at the base of each tower, thence, passes longitudinally along each side rail to a pulley 48 mounted on the side rail at the base of the forward tower, and, finally, upwardly to the top of the forward hoist and about an aft cable reel and drum 50 mounted there. It will be seen that the winding of cable onto or off of each aft cable drum 50 will raise and lower, respectively, the rear ends of sling beams 43 and 44.

The forward ends of sling beams 43 and 44 and forward sling 36 operate the same way as the aft ends and sling. The forward end of each of the sling beams is supported by raising and lowering cables 51 dead-endedat the upper end of a forward hoist tower. Each cable 51 passes through block and pulley 45 at an end of a beam and, thence, to a forward cable drum and reel 52 mounted atop the forward hoist.

There is preferably a cable reel drive 53 and drive motor 54 atop each tower of forward hoist 20. The motor 54 and drive 53 atop each tower is connected to the lifting and lowering cables associated with the sling beam on its side of the crane. By using a small motor shaft pulley and a large drive pulley on the cable reel and drum shaft, a relatively small motor can be employed to lift a substantially heavy load at a reasonable speed. In the model of the preferred embodiment mentioned above, the motors may be 1 15-volt or 230-volt, single-phase electric motors which, with the pulley arrangements of the drive mechanism and the raising and lowering cables, provide a hoisting speed of approximately 3 feet per minute.

Folding legs 11 are preferably provided at the forward end of U-shaped frame 14 as indicated particularly in FIG. 2 of the drawings. Any suitable arrangement of support may be employed. Similarly, a hitch pin 12 and mounting structure 13 is rigidly fastened at a central position on the forward side of the transverse member 17 comprising the U-shaped frame. Any suitable arrangement may be provided at this point for accomplishing connection of the crane to a tractor. It will be understood that this invention comprehends trailers having forward and rear axles as well as single-axle types such as the preferred embodiment described above.

In operation, the crane is placed astride a boat well by backing it, aft end first, and with the wheels tracking along runways or banks on either side of the boat well. When the trailer is in position, the sling beams on each side are lowered. In turn, the slings are lowered. The sling beams are lowered until the slings hang far enough below the water surface to permit the boat to be lifted to float over them and into the well and between the side rails of the crane. When the boat ispositioned in the well and the slings are located at appropriate points along the length of the boat, taking into consideration its hull structure and weight distribution, the cable for raising and lowering the sling beams are shortened by reeling the cable onto their drums. The slings which pass under the boat are now raised up and cradle the boat, lifting it out of the water. It will be noted that the boat can be driven freely over the boat slings and into a position between the side rails and aft hoist towers without obstruction or interference in any way from the boat frame structure. The unlimited inside clear height at the aft hoist and the substantial inside clear height at the forward hoist permit the crane to accommodate most, if not all, power boat superstructures as well as sailboats with stepped and stayed spars since the maximum height and spar location will almost always be aft of the location of the forward hoist. Any harmful or objectionable distortion of the boat crane when it is loading and supporting the full weight of a boat is resisted by the unitary nature of its assembled U- shaped frame and fixed forward hoist structure. Side thrusts imposed upon the towers of the aft hoist are effectively resisted by the large average transverse dimension tubular side rail members. The model of the preferred embodiment referred to above is rated for a -ton capacity and is comparable in overall dimensions to conventional boat cranes of a similar type and capacity which have and are required for successful operation to have transverse members at the aft end which limit the inside clear height at the entrance or aft end of the crane.

When the boat is lifted clear of the walls surrounding the well, the trailer may be moved off the well and the boat transported as desired.

When the boat is to be launched, the trailer bearing the boat is backed astride the well, the lowering and raising cables unreelecl, and the boat lowered in the slings into the water until it floats free of the slings. Without further modification or opening and closing of structural elements of the trailer, the boat, its superstructure and/or stepped spar in place, is eased sternward from the well and out of the slings hanging down into the water from the crane.

It will be apparent that this invention provides a solution to the shortcomings and disadvantages or previously known straddle-type cranes when used to remove and replace boats from and in the water and to transport them on land. These advantageous results have been accomplished by proceeding directly contrary to the teachings of prior inventors in the field; i.e., by eliminating the heretofore considered necessary transverse structural member at the aft end of the crane through which a boat to be handled must enter and leave. The successful elimination of any such transverse member is made possible to a large extent by the unitary structure resulting from a fixed forward hoist rigidly connected to an integral frame, the side rails of which comprise tubular rails having large average transverse dimensions.

While the invention is described above as embodied in a two-wheel or single-axle trailer-type crane, the invention comprehends four-wheel or twoaxle trailer types as well as selfpropelled cranes. It will be apparent, for example, that the particular embodiment shown in the drawings and described above can be modified by replacing folding legs 11 by conventional steerable wheels and by adding a conventional power means mounted on frame 14 for driving wheels 10, all without departing from the invention disclosed and claimed herein. In the case of the self-propelled embodiment, it may be advantageous to omit a transverse frame member corresponding to transverse member 17 in the single-axle trailer embodiment shown. This allows the crane to approach and straddle a boat or other load while moving forward if the forward hoist permits. The same advantageous results are achieved in the trailer and self-propelled types of cranes embodying this invention and such results are totally and equally unexpected in both types of cranes in light of the prior practices and teachings known toa plicant.

The pre erred embodiment of this invention IS able to do anything that can be done by any previously known and comparable cranes, yet is free of the operational limitations and problems inherent in their essential structure. Obviously, the invention disclosed herein is not limited in its application to cranes solely for handling boats. Other loads requiring un limited clear height aft in the crane can be accommodated as well and with the same advantage as can boats.

Those skilled in the art will appreciate that various changes and modifications can be made in the apparatus described herein without departing from the spirit and scope of the invention.

I claim:

1. A straddle-type crane comprising a frame having laterally spaced apart, longitudinally extending tubular side rails unjoined at least at their laterally opposite one ends to provide an open end to the frame, said tubular side rails having a large average transverse dimension to provide rails having a substantial resistance to bending in all directions and to twisting about their axes,

means for movably supporting the frame generally horizontally above the ground,

a forward hoist extending transversely of and spanning the distance between the rails at a point between their ends, said forward hoist being substantially rigid and rigidly mounted on and connected to the side rails,

an aft hoist adjacent the open end of the frame and comprising a substantially stiff member rigidly mounted on and connected to and extending upwardly from the other end of each of the side rails and substantially clear of the space between them, each upwardly extending member being independent of and free of any transverse structural connection with the other,

forward sling means adjustable vertically with respect to and supported from said forward hoist at two laterally spaced apart points and substantially spanning the distance between the rails and aft sling means adjustable vertically with respect to and supported from both of said upwardly extending members and spanning the space between them.

2. The straddle-type crane of claim 1 in which the side rails of the frame are joined together at their laterally opposite other ends to provide a closed end to the frame.

3. The straddle-type crane of claim 1 in which the side rails have a largediameter circular section.

4. The straddle-type crane of claim 1 in which the side rails have structural reinforcement in a plane normal to their axes and adjacent the upwardly extending members mounted thereon, the reinforcement tending to strengthen the tubular side rails against collapse of their sections under operating loads.

5. The straddle-type crane of claim 4 in which the means for movably supporting the frame comprise at least one wheel associated with each rail, each such wheel being mounted for rotation on an axis normal to the longitudinal axis of its associated rail and substantially vertically beneath the upwardly extending member of the aft hoist mounted on its associated rail. 

1. A straddle-type crane comprising a frame having laterally spaced apart, longitudinally extending tubular side rails unjoined at least at their laterally opposite one ends to provide an open end to the frame, said tubular side rails having a large average transverse dimension to provide rails having a substantial resistance to bending in all directions and to twisting about their axes, means for movably supporting the frame generally horizontally above the ground, a forward hoist extending transversely of and spanning the distance between the rails at a point between their ends, said forward hoist being substantially rigid and rigidly mounted on and connected to the side rails, an aft hoist adjacent the open end of the frame and comprising a substantially stiff member rigidly mounted on and connected to and extending upwardly from the other end of each of the side rails and substantially clear of the space between them, each upwardly extending member being independent of and free of any transverse structural connection with the other, forward sling means adjustable vertically with respect to and supported from said forward hoist at two laterally spaced apart points and substantially spanning the distance between the rails and aft sling means adjustable vertically with respect to and supported from both of said upwardly extending members and spanning the space between them.
 2. The straddle-type crane of cLaim 1 in which the side rails of the frame are joined together at their laterally opposite other ends to provide a closed end to the frame.
 3. The straddle-type crane of claim 1 in which the side rails have a large-diameter circular section.
 4. The straddle-type crane of claim 1 in which the side rails have structural reinforcement in a plane normal to their axes and adjacent the upwardly extending members mounted thereon, the reinforcement tending to strengthen the tubular side rails against collapse of their sections under operating loads.
 5. The straddle-type crane of claim 4 in which the means for movably supporting the frame comprise at least one wheel associated with each rail, each such wheel being mounted for rotation on an axis normal to the longitudinal axis of its associated rail and substantially vertically beneath the upwardly extending member of the aft hoist mounted on its associated rail. 